Co-existence of clonal expanded autologous and transplacental-acquired maternal T cells in recombination activating gene-deficient severe combined immunodeficiency.

[omenn syndrome]

It is commonly accepted that the presence of high amounts of maternal T cells excludes Omenn syndrome (OS ) in severe combined immunodeficiency (SCID ). We report a SCID patient with a novel mutation in the recombination activating gene (RAG )1 gene (4 -BP DEL .1406 TTGC ) who presented with immunodeficiency and OS . Several assays , including representatives of specific T cell receptors (TCR ), Vβ families and TCR-γ rearrangements , were performed in order to understand more clearly the nature and origin of the patient 's T cells . The patient had oligoclonal T cells which , based on the patient-mother human leucocyte antigen (HLA )-B 50 mismatch , were either autologous or of maternal origin . These cell populations were different in their numbers of regulatory T cells (T (reg )) and the diversity of TCR repertoires . This is the first description of the co -existence of large amounts of clonal expanded autologous and transplacental-acquired maternal T cells in RAG 1 -deficient SCID .